Coal stoker



Oct. 17, 1939.

J. .F. MEDl JNA COAL STOKER Filed Aug. 22, 1956 2 Sheets-Sheet 1 IN V EN TOR.

A TTORNEYS.

0a, 17, 1939. J. i=. MEDUNA coAL STOKER Filed Aug. 22, 1956 2 Sheets-Sheet 2 INVENTOR. I JEHN F. lVfDU/M MN ATTORNEYS.

Patented Oct. 17, 1939 UNITED STATES PATENT OFFICE 2,176,092 j coa'r. s'roxna John F. Meduna, Seattle, Wash. Application has 22, 1936, Serial No. 91,435

2 Claims. (Cl. 198-213) a stoker for uniformly feeding coal over grate surfaces of extended length by means of a feed screw disposed lengthwise thereof and on whichscrew, stops or dams are fixed at such intervals of spacing, and which are so graduated in size,

as to cause a uniform distribution of the coal onto the grates throughout the entire length of the grate bed.

Still further objects reside in the details 0 construction and in the combination of parts and in their mode of operation, as will hereinafter be described.

It is also a particular object of the invention to provide a feed screw that is applicable to the present requirements as well as to others.

In accomplishing these objects, I have provided the improved details of construction, the preferred forms of which are illustrated in the accompanying drawings, wherein Fig. 1 is a top, or plan view, of a coal stoker embodied by the present invention, a part of the separator plate being broken away' for better illustration.

Fig. 215 a central, longitudinal section of the same, particularly illustrating the novel feed screw and the dams fixed thereto.

Fig. 3 is a cross section on the line 3-4 in Fig. 1.

Fig. 4 is a cross section on the line 4-4 in Fig. l.

Fig. 5 is a detail of the feed screw arrangement.

Referring more in detail to the drawings In its present preferred form of construction, the stoker comprises a grate supporting housing I, having opposite side walls 22,' a bottom wall 3 of trough-like form, as shown best in Fig. 4, and opposite end walls ll, as seen in Fig, 2. Medially of, and extending the length of, this housing is a coal delivery trough 5 having a bottom wall 5a of semi-cylindrical form from which extendthe opposite side walls Fab-5b, which are outwardly and horizontally flanged along their top edges, .as at 6, to form supports cooperating with the side walls 2-2 of the housing to mount the grate plates 1.

By reference to Fig. 4, it will be observed that the housing I, together with the trough '5 and the grates I, forms an enclosure. The top surface of this enclosure is horizontal and forms the fire bed, and is centrally divided by the longi- 5 'tudinal trough 5 from which coal is discharged inopposite directions over the fire bed.- Coal is fed to the stoker from a storage hopper J ll ,which, at its lower end, opens into a horizontally disposed feed tube H which tube, iinturn, opens 19 at one end directly into the trough 5 coaxial of its cylindrically curved base portion, as seen in Fig. A coal feed screw l2 extends/the length of tube H and continues the length of trough 5.

At its outer end the feed screw shaft l2a is 15 provided with a driving wormgear l3, driven by a worm 14 on a supporting shaft l5 revolublymounted in a gear housing It that is fixed in the outer .end of the tube H. The shaft 5 is rotatably driven by an electricimotor l8 that is 20 -mounted upon the housing 18; the driving connection comprising a belt i9 extended about belt pulleys 20 and 2| fixed, respectively, on the me- I tor shaft and worm shaft, as shown in Fig. 2.

' coal, and from there on they are of increased di- 35 ameter so that each will check a certain percentage of the advanced coal and will cause it to .be delivered directly upward in the trough. Thus, by the proper proportioning of the dams with reference to diameter and by properly spacing them, coal may be caused to progress the entire length of the trough and to be fed upwardly and to spread laterally to uniformly cover the grates or fire bed at both sides of the trough.

To insure the lateral spreadof the coal de- 45 livered from the trough, a horizontally disposed baffle plate 30 is fixed directly over the open top of trough 5 and spaced therefrom, as seen in Fig.

4; this plate being supported from the opposite end walls 44 ofthe housing I. 50

The grate plates I are disposed side by side as seen in Fig, 1 and rest at their ends upon supporting ribs 30 and 3|, formed, respectively, on the walls 2 and flanges 8. Each grate plate is formed with a plurality of parallel slits 33 55 iii through which air is discharged from the housing to feed the fire.

Air is forcibly delivered into the housing 9 through a supply tube that leads from a fan housing 36. The tube enters the housing at one end as shown in Fig. 3. A fan this contained in housing 36 and is driven by its mounting chart it which is allned with and directly connected pressure and flow of air upwardly through all plates in the grate area is eilected.

Supported longitudinally of, and at opposite sides of the grate area, are ash troughs ii-86;

adapted to receive, therein the ashes discharged from the grates. Each trough contains a feed screw 46 and these are revolubly driven; respectively, by sprocket chain belts 41 and I8, operating over sprocket wheels 49 on the feed screw shafts and sprockets 50 on a driven shaft I. This latter shaft is revolubly supported at its ends in bearings Hand 53 and is driven by a sprocket chain belt 54 operating about a sprocket wheel 55 keyed on worm shaft Ila and about a sprocket 56 on the shaft ii.

In order that all clinkers may be broken up and also as a means of reducing the ashes to fine condition for easy removal, there is provided along the longitudinal outer edge of each grate,-

an oscillating plate ill supported at its ends by pivots 6| revoluble in bearings .62. At one end of each plate 604s an arm 63 and thesearms are connected by links it with collars .65, fitted revolublyabout eccentrics 66 and 68' on the shaft 5!. Thus, incident to rotation of shaft .il, there will be an oscillating action of the plates causing them to sweep across the outer edges of the fire bed to break off all projecting ash and deliver it into the corresponding trough.

4 Operation of the feed screws in the troughs aivaoaa causes the ashes to be advanced and discharged from one end thereof into suitable receptacles, not herein shown.

While the present invention resides primarily in the combination of parts, comprising the coal stolrer, there is also the novel features of construction in the feed screw 52, which make it ap plicable to various uses other than in coal stokers. For instance, a feed screw similar to that utilized in feeding the coal into the stoker could be used to great advantage to deliver materials along a trough or tube and to deliver the material from the trough at designated intervals. One example of use might be in connection with grain con- ,veying apparatus, for it should be quite evident that by a proper spacing of the dams on the shaft, and by properly graduating them in diameter, a lateral delivery of grain, or other similar substance, from the screw could be obtained in desired amounts.

The use of the present feed screw makes possible 9. practical and satisfactory discharge of coal along the extent of the screw,-so that an even and uniform feeding of coal to the entire grate area results. i

Having thus described my. invention, what I 1 claim as new therein and desire to secure by Letters :Patent is--- 1. A feeding device comprising a trough and a feed screw of uniform diameter throughout its length revolubly contained therein, and dams 

